Micro-Electro-Mechanical Systems (MEMS) are used in a wide variety of applications including, for example, commercial, automotive, aerospace, industrial, and medical application. Micro-Electro-Mechanical Systems (MEMS) can include miniaturized mechanical and electro-mechanical elements (i.e., devices and structures) that are made using microfabrication techniques. MEMS systems can include a wide variety of devices and/or systems including microsensors and microactuators.
An example MEMS microsensor is a pressure sensor. Pressure sensors are often formed by anisotropically etching a recess into a back side of a silicon substrate die, leaving a thin flexible diaphragm. In operation, at least one surface of the diaphragm is exposed to an input pressure. The diaphragm deflects according to the magnitude of the input pressure, and this deflection creates a change in the resistance of the piezoresistors. The change in resistance of the piezoresistors is reflected as a change in an output voltage signal from a resistive bridge formed at least in part by the piezoresistors. In some cases, the diaphragm may be made thinner with the addition of support bosses, which may help increase the sensitivity of the diaphragm over a flat plate diaphragm.
The cost of a MEMS die is often directly related to die size. The die size of MEMs devices that have a recess or cavity, such as pressure sensors or other MEMS devices, is often driven by the structure of the recess or cavity. What would be desirable is a MEMS device with an improved recess or cavity structure that helps reduce die size while still achieving good device performance.